Avoidance and mitigation of frontal collisions while driving a vehicle sometimes requires hard braking. However, attempts to avoid frontal collisions may cause, or may increase the severity of, a rear collision occurring as part of the same event. Rear collisions may also occur due to another vehicle approaching the vehicle from behind at too great of a speed. Existing mechanisms may not adequately account for speeds, speed changes, and other behaviors that can lead to rear-end and/or frontal collisions. This is particularly true in environments where vehicles that are operated autonomously or semi-autonomously, e.g., with no or limited driver intervention, share a roadway with one another and/or with vehicles that are operated manually, i.e., according to conventional driver inputs to accelerator and brake pedals, to a steering wheel, etc.